About 12,000 BCE, a landslide sealed the cave's entrance, thus preserving its contents until its accidental discovery in the late 19th century.
Like many similar prehistoric caves, Altamira has been dogged by environmental and conservation problems.
In 1985, Altamira was declared a UNESCO World Heritage site.
In 2008, UNESCO added 17 additional caves to the Altamira World Heritage Site.
The actual subterranean complex itself consists of a 270-metre long series of twisting passages ranging from 2-6 metres (about 7-20 feet) in height, in which more than 100 animal figures are depicted.
The first significant research into the age of Altamira's rock art was done by French paleolithic scholars Andre Leroi-Gourhan and Annette Laming.Advances in radiocarbon dating by accelerator mass spectrometry now make it possible to date prehistoric cave paintings by sampling the pigment itself instead of relying on dates derived from miscellaneous prehistoric remains recovered in the vicinity of the paintings.Presented below are some radiocarbon dates obtained at the 'Laboratoire des Sciences du Climat et de l'Environnement' for charcoal used in the execution of prehistoric paintings decorating two French caves: Cosquer and Chauvet.First discovered in 1868, though not fully appreciated until the 1900s, Altamira was the first of the great caches of prehistoric art to be discovered, and despite other exciting finds in Cantabria and southern France, Altamira's paintings of bisons and other wild mammals are still the most vividly coloured and visually powerful examples of Paleolithic art and culture to be found on the continent of Europe.As usual, archeologists remain undecided about when Altamira's parietal art was first created.
Search for cave dating:
The cave was first discovered in 1868 by Modesto Peres, a local hunter searching for his dog, but it wasn't until 1879 that the murals on the ceiling of the cave were spotted by Marcelino Sanz de Sautuola a local nobleman and amateur archeologist, when excavating the cave floor for artifacts.